This invention relates to a microfluidic arrangement for metering and separating one or more first metered amounts of liquid from a second amount of liquid.
The existing art discloses various such microfluidic arrangements. These microfluidic arrangements are used for example for metering and injecting liquids for wet chemical, biochemical and diagnostic analyses. Here, among others, volumetric elements are filled with a defined first liquid amount. This defined amount of liquid is separated from a excess second amount of liquid. Currently the separation of the excess amount of liquid from the metered amount of liquid takes place generally by mechanical elements or by a gaseous phase. The gaseous phase can be obtained by exhausting the excess amount of liquid. It is likewise possible for the excess amount of liquid to be “blown away” from the metered amount of liquid by means of a pressure surge.
One disadvantage in the existing microfluidic arrangements for metering and separating by means of a gaseous phase is that to produce the negative pressure or the overpressure (exhaust or blow away) for separation of the first from the second amount of liquid there must be pressure generation means which produce the necessary pressure surge. Conversely, for metering itself a pressure surge is not necessary since the amount of liquid, which is to be metered, is often added to the metered volume via capillarity. This is disclosed for example in publication WO 99/46 045. Basically the metering could also take place with pressure generation means by suction or blowing in. This possibility however proved complicated in the past and where possible it is being replaced by filling by means of capillarity.